When I ask myself why, it isn’t because any aspect of the case is new. Teenagers commit violent acts every day. Drugs distort millions of lives, homelessness is rampant and good parenting is not a given.

The life circumstances of the people involved in this case don’t surprise me. My whys come from sadness and disappointment. Why do the systems we have in place to deal with young people, families and public safety allow a family with so many previous encounters with those systems to arrive at this point?

There is a lot more to learn about this case before anyone can chronicle what went wrong with this family. But even now it’s clear multiple systemic and individual failures had to contribute to what happened last week.

Taken together, they suggest to me that the public response to complex problems isn’t adequate. Part of the reason is that we, the public, think too much in terms of individual choices, without taking into consideration the context for those choices.

In other words, a society that believes people just decide to be good or bad, or maybe are born that way, is not very likely to intervene in a constructive, systemic, coordinated way when problems first become apparent.

No one could have predicted the actions these three are accused of, but a lot of people could have seen trouble ahead. Stories about the case are full of red flags that don’t require hindsight to see.

The brothers being held are 13, 16 and 17. Police believe they walked into a homeless encampment known as The Jungle and shot five people on Jan. 26. Two were shot multiple times and died of their injuries, Jeannine Zapata, 45, and James Quoc Tran, 33.

An informant identified the boys and told police they lived with their mother in a tent near Safeco Field. A tent. Police arrested them there Monday, after the boys allegedly sold one of the guns to an informant on Saturday.

The oldest brother has been convicted in the past of robbery and theft for crimes committed mostly when he was 12.

Two years ago, the now-16-year-old was charged with robbery (taking a backpack from a fellow middle-school student), and last year he and some friends reportedly hijacked a taxi and led police on a chase. An officer reported the teen said the chase was “fun and exciting.”

The 13-year-old has been arrested before, too, and police said he laughed while talking about the shootings with an informant.

I’ve known people from stable, prosperous families who’ve wound up using and even dealing drugs and doing other crimes.

There’s no 100 percent guarantee of an optimum outcome for children, but these three apparently started with a lot going against them.

They came into contact with the criminal-justice system, but that contact didn’t steer them to a better path.

School officials and the child-welfare system should have known about their circumstances and made some effort on their behalf.

Maybe individuals did, but for some reason it didn’t work. We’ll probably learn more about that as the case progresses.

We need to understand because many children slip through our systems every day, and that shouldn’t happen.

We are fortunate to live in a community in which many political and social leaders recognize the need for a more robust and coordinated response to the challenges children face.

That awareness needs to permeate the community so that voters believe it is possible to do better and push for that, and so that people who interact with children get the training and resources they need to make a difference.

This case highlights the web of problems that have to be addressed if we want a safer, more humane community.

We need to fight poverty, to fight easy access to guns, to make access to drug counseling more available, to do something more about homelessness, to make high quality education accessible to all children.